Atari 2600 HDMI-Mod Theory

[S3nda8a]

Hello, I have an Atari 2600 and modified it for S-Video Out.

While researching, I found the RGB mod as a circuit board by Tim Worthington. As far as I understand, his kit accesses the information from the TIA, does a kind of rastering (simply put) and outputs an RGB signal.

 

Because of how an Atari 2600 works, an emulator has to do (almost) the same thing. So there should be a part in an emulator that translates the information from a virtual TIA into video information.

 

I wondered why you can't connect the outputs of an original TIA from an Atari 2600 to the input pins of the RaspberryPi and use the emulator video part to generate a clean HDMI signal.

 

I'm sure I'm completely off the mark here and I certainly don't have the skills to even begin to program such a thing, but what technical hurdle actually speaks against it?

 

Greetings from Germany, Peter.

[+SvOlli]

If you want to go this way, it might be easier just to go for Stella, as it is so close to being perfect. And most of the shortcomings can be overcome with some work:
- if you want "instant on", you can port it to bare metal

- if you want to plug in a cartridge, you can go for my dumper

- there's enough hardware equipment to connect original controllers to PC / Raspberry Pi

 

If you really want to tinker around with a Raspberry Pi running Stella only, I can offer you build-kit, that allows you to create an image with a Linux distribution starting directly into Stella. It's an additional layer for a well respected distribution build system "buildroot", so it's quite future-proof.

 

Greetings back from Hannover, Germany, too

SvOlli

[Windless]

You don't need to emulate the TIA. You can also intercept the write to COLxx registers and inject fake colors. This way you can :

 

-Know which object need to be displayed in which color

-Know which object is currently displayed (by reading just the LUMx pins since you injected fake colors - they are way easyer to read than the COLOR signal)

 

This can (almost) be done with a ROM and a few logic gates and buffers.

 

[+Muddyfunster]

As SvOlli says, there are lots of ways you can get 2600 output (emulated) to HMDI.

 

Looking further afield, there are a projects on other platforms that use the RPI  to intercept or read video memory or video output.

 

I'm not a hardware technical person so these methods probably wouldn't be applicable to the 2600 architecture, I'm also not going to try to give technicals, if they sound interesting, visit the project links.

 

https://www.bytedelight.com/?page_id=1800 I use this on my Spectrum +2, gives HDMI out via a RPI zero by (i think) reading the video memory of the spectrum via the expansion slot and piping that to the pi.

 

https://stardot.org.uk/forums/viewtopic.php?f=3&t=14430 this one started off as an RGB to HDMI project for the BBC and Electron as the both have a nice RGB signal to work with right out of the box. It was then adapted to work on other platforms.

 

I'm not suggesting either would work on the trusty 2600, i've linked them purely for those folks that have a technical interest in this stuff (the second link, I barely follow 1/2 what is being said  ). I love old hardware and getting it to do stuff that it maybe wasn't designed to do but I'm more of a "follow the instructions of someone that knows what they are doing" kind of guy rather than a trailblazing pioneer.